The agent is supervised by systemd --user, and this has its own bus (the one
you get by default), but I am using eval "$(dbus-launch)" then, because I
have multiple X sessions, and an own DBUS session bus helps with separating
them.
The problem is that pinentry is getting launched by the supervised agent, not
the gnupg cli, and therefore uses the wrong/old DBUS_SESSION_BUS_ADDRESS.

I've also noted that the following patch seems to never have been applied to the master branch?!